Diode lasers provide inexpensive, high-efficiency production of laser light in the near infrared spectrum. This laser light has a number of uses. Optical pumping of laser amplifier material with several diode array bars can be used for producing a single high-quality laser beam from the separate beams of the diode array. One promising avenue for producing a single high-quality very high power laser beam is the use of diode pumping of alkali metal vapor, a Diode Pumped Alkali Laser (DPAL).
The efficiency and productivity of these applications require that the individual diode bar pump beams be prepared with optimal properties, such as stable central wavelength, narrow linewidth, low divergence, and uniform intensity.
Applicant in U.S. Pat. No. 7,769,068, incorporated herein by reference in its entirety, describes a system to increase the brightness of, and control gaps in, the light from an external cavity, spectrally narrowed, stack of diode laser bars by employing a stepped mirror, transparent plates, or some combination thereof in the external cavity.
The present invention addresses shortcomings in the art by providing scalable pump sources for optimizing a diode laser pump source. The laser design of the present invention advances Applicants' previous work for spectrally-narrowing stacks of diode laser array bars using a single external cavity outfitted with a proprietary step-mirror. In particular, the present invention can achieve a higher intensity of spectrally-narrowed, low-divergence output of a larger number of laser diode bars. In order to achieve high quality, high-intensity output beams, the light that is amplified in the single-stripe diode can be customized by arranging external optical elements to inject seed photons from the external cavity into the diode, and lock the wavelength and narrow the slow axis divergence. The system and method of the present invention multiplies by twenty, fifty, one-hundred fold or more the number of stacks that can be used in the pump laser system, vastly increasing the attainable power output.